| abstract |
To provide a modified polybutylene terephthalate resin which is reduced in the amount of gas (such as tetrahydrofuran) generating in high-temperature service and in the amount of sublimate generating in a molten state. n A process for preparing a polyester by polycondensing an acid component comprising terephthalic acid or an ester thereof with a lower alcohol as a main component with a diol component comprising 1,4-butanediol as a main component through esterification or transesterification, wherein at least one specified sulfonic acid compound is added in an amount of 0.001 to 0.5 mole % based on the acid component prior to the completion of the polycondensation. |